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SDM

SDM, or Sequence Determined Mapping, is a powerful technique used in genomic research to map and analyze DNA sequences.
It involves the systematic identification and ordering of DNA fragments to construct a comprehensive representation of a genome.
SDM enables researchers to uncover the genetic makeup of organisms, facilitating the study of gene structure, function, and evolution.
This technique is widely employed in a variety of applications, including disease gene discovery, population genetics, and evolutionary biology.
By providing a detailed, high-resolution view of the genome, SDM has become an indispensable tool in the field of molecular biology, contributing to our understanding of the complex genetic landscapes that underpin living systems.

Most cited protocols related to «SDM»

We chose six species distribution models: BIOCLIM, DOMAIN, MAHAL (Mahalanobis distance), RF (random forests), MAXENT (maximum entropy), and SVM (support vector machine). These six SDMs are widely used in academic research and species conservation [16] , [17] , [33] , [34] .
The BIOCLIM model uses environmental data of all known species distribution points and can determine the range of weather conditions suitable for species occurrence. The percentile distribution of every climatic variable within each grid in the species distributions zone is used for multivariate analysis. If the ranges of all climatic variables in the grid are within boundaries appropriate for that species, the BIOCLIM model indicates that this place is suitable [8] , [17] .
The DOMAIN uses a point-to-point similarity metric based on the Gower distance, which is a method for creating a distance matrix from a set of characteristics of species. DOMAIN can assign a classification value of habitat suitability index to each potential site based on its proximity in environmental space to the most similar positive occurrence location [38] . Then, a threshold value of suitability is chosen to determine the distribution boundaries of species’ ecological niche.
The MAHAL model is based on Mahalanobis distance (MD). MD considers the variables correlations in the data set without depending on the scale of measurements. The method ranks the potential sites through their MD to a vector, which can express the mean environmental values of all recorded environmental factors. A certain distance threshold can act as the ecological niche boundaries. These algorithm generate an elliptic envelope which can explicitly explain the possible interrelations between these environmental factors [21] (link).
The RF, a classification and regression tree model, is a combination of tree predictors where every tree can depend on the values of a random vector sampled independently with the same distribution for all trees in the forest [39] , [40] .
MAXENT is based on a machine learning algorithm called maximum entropy, and is based on the principle that species without ecological constraints will spread as far as possible with a distribution as close as possible to uniform [41] .
The SVM is a machine-learning method that belongs to a family of generalized linear classifiers. The principle of SVM is the Vapnik Chervonenkis (VC) dimension and structural risk minimization theory [42] . The SVM model can find the most reasonable way between species adaptability and complexity to yield the most likely distribution according to the limited sample information [43] .
Each of the SDMs was operated with strictly following the modeling technique and using the same 13 environmental variables. Modeling data, advantages and disadvantages were listed in Table S2. We chose “R” as the computing platform and the dismo package to simulate species distribution [44] , [45] .
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Publication 2014
Climate Cloning Vectors Entropy Forests Niche, Ecological SDM Trees
An ensemble of projections of SDM was obtained for the 11,495 selected species. The ensemble included projections with Generalized Additive Models, Boosting Regression Trees, Generalized Linear Models and Random Forests. Models were calibrated for the baseline period using 70% of observations randomly sampled from the initial data and evaluated against the remaining 30% data using the true skill statistic (TSS29 (link)). Presence data were randomly drawn from the gridded range maps. For absences, we considered data in a reasonable buffer around the presence data to avoid having over-optimistic predictive accuracies30 (link). To be consistent with assumed realistic dispersal distances (see next paragraph) and in line with previous analyses, we selected absence data in 2000, 3000, and 4000 km buffer around amphibian, mammal and bird species ranges, respectively. This analysis was repeated four times, thus providing a four-fold internal cross-validation of the models (biomod package15 (link)). The quality of the models was ‘very high’ to ‘excellent’ with an average TSS of 0.83 (Supplementary Fig. 2). Since the quality of the models strongly affect projection uncertainties, we tested three thresholds below which models were removed from projection ensembles. We used a threshold of TSS = 0.4, which is usually considered a minimum for retaining reliable models29 (link). We also used thresholds of 0.6 and 0.7, and investigated their effects on uncertainties of species-based sensitivity metrics. For all further analyses, the most drastic threshold (TSS = 0.7) was then used (red lines in Supplementary Fig. 2).
For each species, all calibrated models (4 SDMs × 4 repetitions) were then used to project the potential distribution of each species under both current and projected future climatic conditions (Supplementary Fig. 1).
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Publication 2019
Amphibians Aves Buffers Climate Mammals Microtubule-Associated Proteins Optimism SDM Trees
To study the effect of altering the geographic extent of the region modeled (i.e., the area in which the model is trained) on predicted species’ distributions, we first generated SDMs using a wide geographical extent including the entire region of Fennoscandia and north-western Russia (map shown in Figure 3B). Due to the paucity of Falco records in north-western Russia, using a full geographic extent of the region modeled may characterize the realized distribution of species in the genus poorly. Including large areas increases the chance that the model samples pseudo-absences in areas that have suitable conditions for the species but are falsely classified as unsuitable because the species has not been properly sampled in that region [8] . Indeed, choosing the correct extent is not a trivial task since the values where occurrence data are lacking are taken as pseudo-absences that are meant to provide a comparative data set to establish the conditions where a species may occur. If large extents with great environmental variation are selected, predictive models will be dominated by parameters that serve to coarsely discriminate regional conditions and weaken the ability to tease out fine-scale conditions determining presence or absence of species [27] . On the other hand, using a restricted region for selection of pseudo-absences can be a serious error when fitting models to project potential effects of climate change [37] , since future environmental conditions may not be represented. Since occurrence data for our model species was lacking for north-western Russia, we used Fennoscandia, which accurately mirrored the distribution of the occurrence data of the species (map shown in Figure 3A).
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Publication 2012
Climate Change SDM
To determine the effect of cardiorespiratory activity on the distribution of frequency band power for the entire brain, HR and RVT signals were averaged at every TR and the resulting vectors were removed voxel-wise from the BOLD using Matlab linear regression. Of the 17 subjects, 12 subjects were included in the analysis, 1 subject had missing data, and 4 subjects had temporal artifacts in the autonomic signal that could not be corrected by interpolation.
Z-scored SDMs were generated from rapid TR fMRI scans in a similar manner as those obtained with slower TRs. Z-scores for each frequency band were generated by subtracting the mean voxel-wise power for the midline sagittal slice and dividing by the standard deviation. Subject z-score maps were averaged using a fixed-effects model to create group level z-statistic maps. BOLD signal significantly affected by physiological noise was determined by observing the distribution of power around frequency bands known to be associated with cardiorespiratory activity and showing relevant peaks for the group average midline slice BOLD frequency spectrum (0.2–0.4 Hz, and 0.75–1.5 Hz). Regions exceeding z>2.3 for these frequency bands were masked from further analysis of the midline slice. The group average z-score distribution for the slow fMRI data set was obtained using the same mask. BOLD SDMs of the right leg were made in an identical manner to the brain SDMs, without physiologic correction.
Publication 2011
Brain Cloning Vectors fMRI Microtubule-Associated Proteins Nervous System, Autonomic physiology Radionuclide Imaging SDM
Our analysis strategy supports two main and interconnected objectives: (1) to generate forecasts of COVID-19 deaths, infections and hospital resource needs for all US states; and (2) to explore alternative scenarios on the basis of changes in state-enforced SDMs or population-level mask use. The modeling approach to achieve this is summarized in the Supplementary Information and can be divided into four stages: (1) identification and processing of COVID-19 data, (2) exploration and selection of key drivers or covariates, (3) modeling deaths and cases across three boundary scenarios of SDMs in US states using an SEIR framework and (4) modeling health service utilization as a function of forecast infections and deaths within those scenarios. This study complies with the Guidelines for Accurate and Transparent Health Estimates Reporting statement (Supplementary Information).
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Publication 2020
COVID 19 Infection SDM

Most recents protocols related to «SDM»

Results for hierarchical cluster analysis (HCA) of samples and metabolites are presented as heatmaps with dendrograms. Pearson correlation coefficients (PCC) between samples were calculated using the cor function in R (accessed on: 10 December 2021) and presented as only heatmaps. Both HCA and PCC were carried out using the R package pheatmap. For HCA, normalized signal intensities of metabolites (unit variance scaling) are visualized as a color spectrum. Principal component analysis (PCA) was performed with the statistics function prcomp within R. The data were unit variance scaled before PCA. Significantly regulated metabolites (SRMs) between groups were determined by VIP ≥ 1 and absolute Log2FC (fold change) ≥ 1. VIP values were extracted from OPLS-DA results, which also contained score plots and permutation plots, and was generated using R package MetaboAnalystR. The data were log transformed (log2) and mean centered before OPLS-DA. To avoid overfitting, a permutation test (200 permutations) was performed. Identified metabolites were annotated using the KEGG compound database (accessed on: 10 December 2021) and annotated metabolites were then mapped to the KEGG pathway database (accessed on: 10 December 2021). Pathways with the SDMs mapped were subjected to MSEA (metabolite sets enrichment analysis), and their significance was determined using p-values from a hypergeometric test.
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Publication 2023
SDM
We employed LR and ML methods to build ecometric models relating turtle community body size distributions to temperature and precipitation. Our linear models used single- and two-variable predictors from turtle community size mean, SD, maximum, minimum, range, and skewness (SI Appendix).
We adapted the ML approach from ref. 8 , to output the most likely value for the environmental variable for a given trait distribution based on the observed environmental values across turtle communities in a training dataset. This method does not require a predictable relationship between the ecometric statistic values and the estimated climate variable. We extensively tested different techniques for building ML models, using 75% of the available community samples at global and continental scales to train the models and the remaining 25% of data points to test their predictive performance. (SI Appendix).
We compared models built using community sampling points drawn from three different geographic datasets. The first dataset is species range maps from the Turtle Taxonomy Working Group (65 ), and the second is species occurrence points from the Global Biodiversity Information Facility database (https://www.GBIF.org), both of which we used to assemble communities at a set of global sampling points spaced at 50 km across the terrestrial globe. The third input dataset we used is range maps derived from SDMs (66 ). SDMs have not previously been employed in ecometric modeling, but their estimates of geographic areas where environmental conditions are suitable for each species can improve ecometric community sampling, because the SDMs output an approximation of ranges prior to human impacts on geographic distributions.
We also compared ML models using only occurrences of terrestrial or aquatic turtle species to investigate whether body size is more strongly related to climate in turtle communities from one of these habitat categories. We built additional models based only on training points on each continent and compared their predictive performance for temperature and precipitation with that of global models at test points on individual continents (Table 1). We provide the full ranking of models in each run and comparisons of prediction anomalies between datasets, along with all results for precipitation modeling (SI Appendix).
We applied ecometric models to reconstruct temperature and precipitation values for each member of the Shungura Formation based on paleocommunity ecometrics. We inputted these communities into the top-performing models to estimate temperature and precipitation at the member stratigraphic scale.
Publication 2023
Body Size Climate Homo sapiens Microtubule-Associated Proteins SDM Turtle
We used species distribution models which envisage potentially suitable habitat for species based on variables supportive to species occurrences [33 (link)]. Numerous model types are available for developing SDMs; however, maximum entropy (e.g., Maxent) is one of most effective tools for species having limited spatial presence-only data [34 ,35 (link),36 (link)]. Maximum entropy forecasts the species probability distribution of random events with uniform and high stability [37 (link),38 (link)].
We determined potential habitat layers by first selecting 19 bioclimatic variables at 30 arc-second (about 1 km2) resolution from Worldclim [39 (link)] and extracted aspect from a digital elevation model (about 1-km2 resolution; Shuttle Radar Topography Mission (SRTM); https://ita.cr.usgs.gov, accessed on 28 November 2022) (Supplementary Table S1). We selected eight environmental variables including mean annual temperature (Bio_1), mean diurnal range (Bio_02), iso-thermality (Bio_3), annual precipitation (Bio_12), precipitation of driest month (Bio_14), precipitation seasonality (Bio_15), precipitation of coldest quarter (Bio_19), and aspect (see Figure 2) based on jackknife analysis, which uses a leave-one-out approach to estimate variable importance (Supplementary Materials Table S1; Figure S1). We excluded highly correlated (|r| > 0.70) variables to reduce the potential for model overfitting [40 (link)]. We used maximum entropy modeling software (Maxent version 3.3.3 K) [36 (link)] to estimate the potential nesting distribution of Egyptian vultures.
We ran Maxent models using 75% presence data for calibration and the remaining 25% for model validation [41 (link)] using the bootstrapping procedure with 10 replications and a maximum of 500 iterations. We used the default settings for the number of background samples and auto features for model construction. We evaluated model validation and accuracy using the area under the curve (AUC) of the receiver operating characteristics [42 ]. However, because of criticism in the use of AUC for model evaluation [43 (link)], we also evaluated model performance using the true skill statistic (TSS), sensitivity, and specificity [44 (link)]. The TSS values range from −1 to 1, with values approaching 1 indicating good model performance and values <0 indicating performance no better than random. We converted habitat into binary form (suitable or unsuitable) using the 10th-percentile training presence logistic threshold [45 (link)] and used the corresponding raster layer to identify suitable potential nesting habitat for Egyptian vultures.
We used predicted suitable nesting habitat to identify whether the model correctly predicted nesting habitat as well as existing factors influencing the occurrence of Egyptian vulture nests along the Madi River corridor from Damauli, Tanahu to Tanting, Kaski. This area supports abundant Egyptian vultures and we assumed this abundance reflected their residence in this area, where cliffs and forests occur near human settlements. We established 35 stations at 3-km intervals along 135 km of the Madi River. Each station was 500 m × 500 m and within each we established five 100 m × 100 m plots, four at the corners and one at the center. During October 2020–February 2021, we searched each plot for 3 h, recording the occurrence of Egyptian vulture nests and the presence of Egyptian vultures roosting or feeding. We recorded the occurrence of feeding vultures while sitting quietly at the corner of each plot, and for observations of nesting and roosting we searched throughout the plots. From the center of each plot we recorded the elevation using GPS, and measured the distance to the nearest forest, area of agricultural land, water, and human settlement. We measured the nearest distance to human settlement using a GIS if the area had more than one house and were used for living.
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Publication 2023
DNA Replication Entropy Fingers Forests Homo sapiens Hypersensitivity Rivers SDM
Species distribution modeling was carried out in R (R Core Team 2019 ) using the Maxent algorithm (Phillips et al. 2004 , 2006 (link)) as implemented in the ‘Biomod2’ package (Thuiller et al. 2016 ). We selected 10,000 random points as pseudo-absence data and a split-sample cross-validation was repeated 10 times, using a random subset (30%) of the initial data set. Model performance was evaluated using both the area under the relative operating characteristic curve (AUC—Hanley and McNeil 1982 (link)) and the true skill statistic (TSS—Allouche et al. 2006 (link)).
The suitability maps from model projections were converted into binary distribution maps using three different thresholds implemented in the ‘PresenceAbsence’ package (Freeman and Moisen 2008 (link)): sensitivity equals specificity (Sens = Spec), maximizing the sum of sensitivity and specificity (MaxSens + Spec), and minimizing the distance between the relative operating curve plot and the upper left corner of the unit square (MinROCdist). These thresholds outperform other commonly used thresholds (Cao et al. 2013 (link); Liu et al. 2005 (link)).
We constructed SDMs of both the overall species (hereafter “species model”) and each group of populations (hereafter “core model” and “disjunct model”) over the entire distributional range of the species. In addition, following the approach of Pearman et al. (2010 (link)), we considered the area that was predicted to have suitable climatic conditions in one or both groups of populations as an “aggregate” model for the distribution of the species. To obtain a relative score of “goodness” of the aggregate model, we calculated the mean AUC and TSS values for core and disjunct models, according to Gonzalez et al. (2011 (link)). In addition, for each studied species, we calculated the sensitivity of all types of models as the proportion of occupied sites that are correctly predicted as suitable by the model under current climatic conditions (Pearman et al. 2010 (link)). For SDMs under future climates, we performed an ensemble combining all projections and species were considered occurring in a cell if at least 50% of models projected its occurrence there (i.e., a majority consensus rule).
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Publication 2023
Cells Climate Hypersensitivity Microtubule-Associated Proteins Population Group Scalp-Ear-Nipple Syndrome SDM

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Publication 2023
Anthropogenic Effects Climate Climate Change factor A Factor XIII Homo sapiens Light Livestock MCC protocol Neoplasm Metastasis Physical Examination Plant Dispersal Schopf-Schulz-Passarge Syndrome SDM Wind

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More about "SDM"

Sequence Determined Mapping (SDM) is a powerful genomic analysis technique that enables researchers to comprehensively map and study DNA sequences.
This method involves the systematic identification and ordering of DNA fragments, allowing for the construction of a detailed representation of a genome.
Through SDM, scientists can uncover the genetic makeup of organisms, facilitating investigations into gene structure, function, and evolution.
This versatile technique is widely employed in various applications, such as disease gene discovery, population genetics, and evolutionary biology research.
By providing a high-resolution, in-depth view of the genome, SDM has become an indispensable tool in the field of molecular biology, contributing to our understanding of the complex genetic landscapes that underpin living systems.
Synonyms for SDM include genomic sequencing, DNA mapping, and genome assembly.
Related terms include next-generation sequencing (NGS), bioinformatics, and comparative genomics.
Commonly used abbreviations include NGS, PCR, and BLAST.
Key subtopics in SDM research include genome assembly, sequence alignment, variant analysis, and phylogenetic reconstruction.
Researchers leverage specialized software like GraphPad Prism, ChromaTOF, and SPSS Statistics to analyze and visualize SDM data.
Additionally, tools like BstBI and HOBO Pendant Temperature Data Loggers may be employed in sample preparation and environmental monitoring during SDM experiments.
The GeneArt platform provides advanced gene synthesis and engineering capabilities that complement SDM workflows.
By incorporating these diverse technologies and techniques, scientists can maximize the insights gleaned from SDM, driving advancements in our understanding of genetic systems and their evolutionary trajectories.